According to secondary ion mass spectrometry, a sample is bombarded with an ion beam which is a corpuscular beam, and secondary ions emitted from the sample are subjected to mass spectrometry.
The secondary ion mass spectrometry often employs a powdery sample composed of an electrically insulating material. The electrically insulating powdery sample can be held by the following methods:
(1) A method in which one side of a double-sided adhesive tape is stuck to a support member, and the electrically insulating powdery sample is stuck to the other side.
(2) A method in which the sample is dissolved in a solvent which is then applied onto a holder to vaporize the solvent.
According to the method (1) employing the double-sided adhesive tape which is generally an electrically insulating tape, however, the sample bombarded with the corpuscular beam is charged up and the adhesive easily evaporates to contaminate the inner walls of an evacuated sample chamber in which the sample is held as well as the inner walls of the corpuscular beam passage. Therefore, the corpuscular beam impinging upon the sample is undesirably deflected. With the method (2), the sample is prevented from being charged up provided the sample is not too thickly applied onto the holder. However, the sample is degenerated or contaminated with the solvent.